Batteries, such as primary alkaline batteries, are commonly used electrical energy sources. Generally, a battery contains a negative electrode, typically called the anode, and a positive electrode, typically called the cathode. The anode contains an active material (e.g., zinc particles) that can be oxidized; and the cathode contains an active material (e.g., manganese dioxide) that can be reduced. The anode active material is capable of reducing the cathode active material. In order to prevent direct reaction of the anode material and the cathode material, the anode and the cathode are electrically isolated from each other by a separator.
When a battery is used as an electrical energy source in a device, such as a cellular telephone, electrical contact is made to the anode and the cathode, allowing electrons to flow through the device and permitting the respective oxidation and reduction reactions to occur to provide electrical power. An electrolyte in contact with the anode and the cathode contains ions that flow through the separator between the electrodes to maintain charge balance throughout the battery during discharge.